Plunger impact sensor

ABSTRACT

There is provided a lubricator assembly having a lubricator body having a bottom end in communication with a well, a top end, and one or more production flow ports, a spring within the lubricator body and above the one or more production flow ports, the spring having a movable end and a fixed end above the movable end, the spring being compressible in a longitudinal direction, the spring compressing in response to a plunger return force, a switch above the movable end of the spring, the switch generating a signal when actuated, and an actuator carried by the movable end of the spring, the actuator actuating the switch when the movable end reaches a predetermined position within the lubricator, the predetermined position being reached when the plunger return force is equal to or greater than a predetermined plunger return force.

TECHNICAL FIELD

This relates to an impact sensor for use with a plunger in a hydrocarbon well.

BACKGROUND

In hydrocarbon producing wells, it is generally necessary to assist the fluids to reach the surface. In some wells, primarily gas producing wells (i.e. wells in formations that produce a high concentration of gas-phase hydrocarbons), one system used to assist production involves the use of a plunger, which acts as a piston to lift accumulated liquids.

The plunger is moved upward by gas pressure below the plunger. As a result of factors such as variation in pressure accumulated and the weight of the liquid above the plunger, the plunger may return to the surface at different speeds, some of which may be damaging to the equipment and may be unsafe. U.S. Pat. No. 7,337,854 (Horn et al.) entitled “Gas-pressurized lubricator and method” discusses one design that attempts to reduce the kinetic energy of a plunger, while U.S. Pat. No. 7,219,725 (Chisolm) entitled “Instrumented plunger for an oil or gas well” describes sensor assemblies for measuring the velocity of a plunger.

SUMMARY

According to an aspect, there is provided a lubricator assembly, comprising a lubricator body having a bottom end in communication with a well, a top end, and one or more production flow ports, a spring within the lubricator body and above the one or more production flow ports, the spring having a movable end and a fixed end above the movable end, the spring being compressible in a longitudinal direction, the spring compressing in response to a plunger return force, a switch above the movable end of the spring, the switch generating a signal when actuated, and an actuator carried by the movable end of the spring, the actuator actuating the switch when the movable end reaches a predetermined position within the lubricator, the predetermined position being reached when the plunger return force is equal to or greater than a predetermined plunger return force.

According to another aspect, the actuator may comprise a disc carried by the movable end of the spring.

According to another aspect, the switch may be attached at the top end of the lubricator body and may be in axial alignment with the lubricator body.

According to another aspect, the switch may be actuated by metal to metal contact between the actuator and the top end of the lubricator body.

According to another aspect, the predetermined plunger return force may be indicative of an alarm condition.

According to another aspect, the lubricator assembly may further comprise a controller that receives the signal generated by the switch, and the controller may be programmed to shut in the well upon receiving the signal from the switch.

According to another aspect, the actuator may actuate the switch when the spring is fully compressed.

According to another aspect, the actuator may actuate the switch when the spring is partially compressed.

According to an aspect, there is provided a method of shutting in a well having a wellbore, a lubricator assembly, and a plunger, the lubricator assembly comprising a lubricator body having a bottom end in communication with a well, a top end and one or more production flow ports, the method comprising the steps of placing the plunger in the wellbore of the well, the plunger travelling through the wellbore in response to the pressure in the well, such that in response to sufficient pressure, the plunger travels from the well into the lubricator assembly, the plunger returning to the lubricator assembly with a plunger return force, fixing a spring within the lubricator body and above the one or more flow production ports, the spring having a movable end and a fixed end above the movable end, the spring being compressible in a longitudinal direction, the spring compressing in response to the plunger return force, attaching an actuator to the movable end of the spring, determining a predetermined plunger return force, positioning a switch above the movable end of the spring, the switch generating a signal when actuated, and calibrating the actuator to actuate the switch when the movable end of the spring reaches a predetermined position within the lubricator, the predetermined position being reached when the plunger return force is equal to or greater than the predetermined plunger return force.

According to another aspect, the actuator may comprise a disc carried by the movable end of the spring.

According to another aspect, the switch may be attached at the top end of the lubricator body and may be in axial alignment with the lubricator body.

According to another aspect, the switch may be actuated by metal to metal contact between the actuator and the top end of the lubricator body.

According to another aspect, the predetermined plunger return force may be indicative of an alarm condition.

According to another aspect, the method may further comprise the step of providing a controller that receives the signal generated by the switch, the controller being programmed to shut in the well upon receiving the signal from the switch.

According to another aspect, the actuator may actuate the switch when the spring is fully compressed.

According to another aspect, the actuator may actuate the switch when the spring is partially compressed.

In other aspects, the features described above may be combined together in any reasonable combination as will be recognized by those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

FIG. 1 is a side elevation view in section of a lubricator assembly with a plunger at a lower position.

FIG. 2 is a side elevation view in section of a lubricator assembly with a plunger at an intermediate position.

FIG. 3 is a side elevation view in section of a lubricator assembly with a plunger at an upper position.

DETAILED DESCRIPTION

A lubricator assembly, generally identified by reference numeral 10, will now be described with reference to FIG. 1 through 3. Lubricator assembly 10 is part of a system with a plunger 34 that may be used with a hydrocarbon producing well 16, such as a gas well, in order to assist with production of fluids from well 16.

Referring to FIG. 1, lubricator assembly 10 has a lubricator body 12 with a bottom end 14 in communication with well 16, a top end 18, and one or more production flow ports 20. As shown in FIG. 1, lubricator body 12 has two production flow ports 20. The number of production flow ports 20 may vary depending on the application and the type of lubricator and well. Lubricator body 12 has a spring 22 carried within lubricator body 12 above the one or more production flow ports 20. Spring 22 has a movable end 24 and a fixed end 26 above the movable end 24. Spring 22 is compressible in a longitudinal direction, and compresses in response to a plunger return force, as shown in FIG. 2. As shown, spring 22 is a longitudinal coil spring. While the advantages of using such a spring in the described example are apparent, it will be understood that other types of springs also be used.

Lubricator body 12 has a switch 28 that detects when plunger 34 arrives at a high rate of speed. In particular, switch 28 is used to detect with spring 22 is compressed to a particular point by the kinetic energy of plunger 34. In the depicted example, this is done by placing switch 28 at a point above movable end 24 of spring 22 to be actuated by an actuator 30 when spring 22 is sufficiently compressed. Switch 28 may be positioned at various points on lubricator body 12 above movable end 24 of spring 22. In the depicted example, referring to FIG. 1, switch 28 is located at the top end of lubricator body 12 in axial alignment with lubricator body 12. Alternatively, switch 28 may be located at various positions spaced down from the top end of lubricator body 12, and may be attached along the sidewall of lubricator body 12. Switch 28 generates a signal when actuated, such as a sound, a visual signal, a signal to a computer monitoring system, or the like. While the signal generated may be intended to notify an operator, it may also be used to cause a computer processor to record an event, or both, depending on the requirements and preferences of the user. In a preferred embodiment, switch 28 may be a contact switch, or a proximity sensor, such as a reed switch that is actuated based on the present of a magnet. It will be understood that switch 28 acts to identify an alarm condition, and that other types of switches or sensors may be used, such as a sensor that is designed or programmed to send a signal when a particular condition is reached.

Spring 22 carries an actuator 30 at movable end 24 that actuates switch 28 when movable end 24 of spring 22 reaches a predetermined position within lubricator body 12. The predetermined position is reached when the plunger return force is equal to or greater than a predetermined force, indicative of an alarm condition. Actuator 30 may take a variety of forms, as will be understood by those skilled in the art. For example, actuator 30 may be a disc carried by movable end 24 of spring 22 that triggers a switch or acts as a switch when in the predetermined position. Referring to FIG. 3, the predetermined position may be determined by the dimensions of actuator 30. As shown, actuator 30 may contact top end 18 of lubricator body 12. Switch 28 may be actuated by metal to metal contact between actuator 30 and top end 18 of lubricator body 12. Switch 28 may also be actuated by direct contact between actuator 30 and a component of switch 28. Switch 28 may also be actuated, for example, by actuator 30 passing a certain height in lubricator body 12. Switch 28 may be designed in a variety of ways as will be recognized by those skilled in the art. For example, switch 28 may be a physical switch, a proximity switch, etc. In some cases, switch 28 may be actuated before spring 22 is fully compressed, where switch 28 is actuated at any point along the compression path of spring 22 that is desired. This may provide an extra safety area with further compression available, or may serve other purposes. For example, lubricator body 12 may have two switches 28, the first being placed at a midpoint along the compression path of spring 22, and when movable end 24 of spring 22 passes the first switch 28, actuator 30 actuates the first switch 28, and the first switch 28 communicates with a data recording device to record the impact for review. A second switch 28 may be placed at a higher point along the compression path of spring 22, for example, at or near the top 18 of lubricator body 12. When actuator 30 actuates second switch 28, second switch 28 may generate an alarm condition and shut in the well.

Referring to FIG. 3, movable end 24 of spring 22 may reach the predetermined position when the predetermined plunger return force exceeds a given value. For example, predetermined plunger return force may be indicative of an alarm condition requiring the well to be shut in for repair or diagnosis. Lubricator assembly 10 may have a controller 32 that receives the signal generated by switch 28, and controller 32 may be programmed to shut in well 16 upon receiving the signal from switch 28, or send an alarm to an operator to initiate the shut in. It will be understood that well 16 may be shut in using a variety of methods known in the art. The alarm condition could be determined using a variety of safety thresholds. For example, the alarm condition could be determined by the compressibility and strength of spring 22, in order to prevent a failure condition in spring 22. As one example, actuator 30 may actuate switch 28 when spring 22 is fully compressed. Alternatively, actuator 30 may actuate switch 28 without having to fully compress spring 22

Referring to FIG. 1, lubricator body 12 may also have a catcher assembly 38 for holding plunger 34 above port 20. Lubricator body 12 may also have a pressure gauge 40 for measuring pressure within lubricator body 12. Other accessories and apparatus may also be included in lubricator boy 12, depending on the needs of the user and the application for the plunger assembly.

In operation, plunger 34 is placed in wellbore 36 of well 16, and plunger 34 travels through wellbore 36 in response to the pressure in well 16. When the pressure below plunger 34 is sufficient, plunger 34 travels up through well 16 and into lubricator assembly 12. The speed of plunger 34 will determine the force with which it returns. In order to prevent damage or avoid unsafe conditions caused by the plunger returning with too high a force, the system is designed to trigger a switch when plunger 34 returns with a force greater than a predetermined value and compresses spring 22 sufficiently. Actuator 30 is attached to spring 22, and is calibrated such that actuator 30 actuates switch 28 when a predetermined position is reached by movable end 24 of spring 22. The predetermined position is determined by the predetermined plunger return force, and is achieved when the plunger return force is equal to or greater than the predetermined plunger return force.

Activating switch 28 may cause well 16 to be shut in and an alarm condition generated so that well 16 may be diagnosed and repaired as necessary. The compression of spring 22 is directly related to the force applied to spring 22 by plunger 34, and thereby indicates the force with which the plunger is returning to the surface. Controller 32 may be programmed to respond differently in response to different scenarios. For example, controller 32 may trigger an alarm for review by maintenance personnel in response to a single high impact that activates switch 28, and may close in well 16 only in response to a second high impact that equals or exceeds the predetermined plunger return force. Different responses to activation of switch 28 will be understood by those skilled in the ar.

In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

The scope of the following claims should not be limited by the preferred embodiments set forth in the examples above and in the drawings, but should be given the broadest interpretation consistent with the description as a whole. 

1. A lubricator assembly, comprising: a lubricator body having a bottom end in communication with a well, a top end, and one or more production flow ports; a spring within the lubricator body and above the one or more production flow ports, the spring having a movable end and a fixed end above the movable end, the spring being compressible in a direction parallel to the lubricator, the spring compressing in response to a plunger return force; a switch above the movable end of the spring, the switch generating a signal when actuated by an actuator carried by the movable end of the spring,
 2. The lubricator assembly of claim 1, wherein the actuator comprises a disc carried by the movable end of the spring.
 3. The lubricator assembly of claim 1, wherein the switch is attached at the top end of the lubricator body and is in axial alignment with the lubricator body.
 4. The lubricator assembly of claim 1, wherein the switch is actuated by metal to metal contact between the actuator and the top end of the lubricator body.
 5. The lubricator assembly of claim 1, wherein the switch is magnetically actuated.
 6. The lubricator assembly of claim 1, wherein the actuator actuates the switch when the plunger return force is indicative of an alarm condition.
 7. The lubricator assembly of claim 1, further comprising a controller that receives the signal generated by the switch, the controller being programmed to shut in the well upon receiving the signal from the switch.
 8. The lubricator assembly of claim 1, wherein the actuator actuates the switch when the spring is fully compressed.
 9. The lubricator assembly of claim 1, wherein the actuator actuates the switch when the spring is partially compressed.
 10. A method of shutting in a well having a wellbore, a lubricator assembly, and a plunger, the lubricator assembly comprising a lubricator body having a bottom end in communication with a well, a top end and one or more production flow ports, the method comprising the steps of: placing the plunger in the wellbore of the well such that the plunger travels through the wellbore in response to the pressure in the well, and in response to sufficient pressure, the plunger travels from the well into the lubricator assembly with a plunger return force; fixing a spring within the lubricator body and above the one or more flow production ports, the spring having a movable end and a fixed end above the movable end, the spring being compressible in a longitudinal direction, the spring compressing in response to the plunger return force; attaching an actuator to the movable end of the spring and causing the actuator to actuate the switch when the movable end of the spring reaches a predetermined position within the lubricator indicative of a predetermined plunger return force.
 11. The method of claim 10, wherein the actuator comprises a disc carried by the movable end of the spring.
 12. The method of claim 10, wherein the switch is attached at the top end of the lubricator body and is in axial alignment with the lubricator body.
 13. The method of claim 10, wherein the switch is actuated by metal to metal contact between the actuator and the top end of the lubricator body.
 14. The method of claim 10, wherein the switch is magnetically actuated.
 15. The method of claim 10, wherein the predetermined plunger return force is indicative of an alarm condition.
 16. The method of claim 10, further comprising the step of providing a controller that receives the signal generated by the switch, the controller being programmed to shut in the well upon receiving the signal from the switch,
 17. The method of claim 10, wherein the actuator actuates the switch when the spring is fully compressed.
 18. The method of claim 10, wherein the actuator actuates the switch when the spring is partially compressed. 